package practice_2025_8_21;

import java.util.*;

public class Main {
    /**
     * 神奇的字母
     * @param args
     */
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[] hash = new int[26];
         int max = 0;
        int maxIndex = 0;
        while(sc.hasNext()) {
            String str = sc.next();
            for(char ch: str.toCharArray()) {
                if (ch != ' ') {
                    int index = ch - 'a';
                    hash[index]++;
                    if (hash[index] > max) {
                        max = hash[index];
                        maxIndex = index;
                    }
                }
            }
        }
        System.out.println((char)(maxIndex + 'a'));
    }
}